Thermokinetic studies of organotin(IV) carboxylates derived from para-methoxyphenylethanoic acid

Thremogravimetric (TG) studies of a new series of organotin(IV) carboxylates of the general formula R_nSnL_4-n (where R = CH₃, C₂H₅, C₄H₉, C₆H₅, C₆H₁₁ and C₈H₁₇, n = 2, 3 and L = para-methoxyphenylethanoate anion) have been carried out. Horowitz and Metzger method has been used to calculate thermokinetic parameters. It has been found that diorganotin dicarboxylates have larger activation energy than those of corresponding triorganotin carboxylates. Furthermore, the activation energy, Gibb’s free energy, entropy and enthalpy of diorganotin compounds shows the following trend, (CH₃)₂SnL₂ < (C₂H₅)₂SnL₂ < (C₄H₉)₂SnL₂ < (C₈H₁₇)₂SnL₂. This is attributed to steady increase in chain length of the alkyl groups. However, triorganotin compounds do not show such behavior.     

Sorption and partial molar volume of gases in polybutadiene

Sorption of He, H₂, N₂, O₂, Ar, CH₄, C₂H₆, and C₂H₆ in polybutadiene and the dilation of the polymer due to sorption of the gases are investigated over the pressure range 0-50 atm at 25°C. For CO₂ the measurements are made at temperatures ranging from 15 to 80°C. Partial molar volumes of the gases in the polymer are determined. The temperature dependence of partial molar volume is discussed on the basis of the data for CO₂. The Flory-Huggins interaction parameters of CO₂, C₂H₄, and C₂H₆ are also estimated.     

Solubility of nonpolar gases in 2,2,2-trifluoroethanol at 25°C and 101.33 kPa partial pressure of gas

Solubility measurements of several nonpolar gases (He, Ne, Ar, Kr, Xe, H₂, N₂, CH₄, C₂H₄, C₂H₆, CF₄, SF₆, and CO₂) in 2,2,2-trifluoroethanol at 25°C and 101.33 kPa partial pressure of gas are reported. Gibbs energy for the solution process at 25°C is evaluated from the experimental values of the solubility of gases expressed as mole fraction. Lennard-Jones 6–12 pair potential parameters for 2,2,2-trifluoroethanol are estimated by using the scaled particle theory (SPT); and experimental solubilities are compared with those calculated from the values of these parameters through the SPT model.     

Total cross sections for electron scattering by polyatomic molecules at 10–1000 eV: C2H2, C2H4, C2H6, C3H6, C3H8 and C4H8

A model complex optical potential (composed of static, exchange, polarization and absorption terms) is employed to calculate the total (elastic and inelastic) electron-atom scattering cross sections from the corresponding atomic wave function at the Hartree-Fock level. The total cross sections (TCS) for electron scattering by their corresponding molecules (C₂H₂, C₂H₄, C₂H₆, C₃H₆, C₃H₈ and C₄H₈) are firstly obtained by the use of the additivity rule over an incident energy range of 10–1000 eV. The qualitative molecular results are compared with experimental data and other calculations wherever available, good agreement is obtained in intermediate-and high-energy region.     

Solubility of nonpolar gases in tetrahydrofuran at 0 to 30°C and 101.33 kPa partial pressure of gas

Solubility measurements of several nonpolar gases (He, Ne, Ar, Kr, Xe, H₂, D₂, N₂, CH₄, C₂H₄, C₂H₆, CF₄ and SF₆) in tetrahydrofuran from 0 to 30°C and 101.33 kPa partial pressure of gas are reported. Thermodynamic functions for the solution process (Gibbs energy, enthalpy, and entropies) at 25°C are evaluated from experimental values of gas solubility as mole fractions and their variation with temperature. Lennard-Jones 6–12 pair potential parameters for tetrahydrofuran are estimated using the scale particle theory; experimental solubilities as mole fraction are compared with values calculated using this theory.     

Solubility of nonpolar gases in tetrahydropyran at 0 to 30°C and 101.33 kPa partial pressure of gas

Solubility measurements of several nonpolar gases (He, Ne, Ar, Kr, Xe, H₂, D₂, N₂, CH₄, C₂H₄, C₂H₆, CF₄, and SF₆) in tetrahydropyran at the temperature range 0 to 30°C and 101.33 kPa partial pressure of gas are reported. Thermodynamic functions for the solution process (Gibbs energy, enthalpy, and entropies) at 25°C are evaluated from the experimental values of the solubility of gases as mole fraction and their variation with the temperature. Lennard-Jones 6–12 pair potential parameters for tetrahydropyran are estimated by using the scale particle theory (SPT); and experimental solubilities are compared with the calculated values using this model. Experimental solubilities of gases in tetrahydropyran and intermolecular potential parameters are compared with those obtained for the same gases in other cycloethers.     

Kinetic formation of CO,CO2, H2, and light hydrocarbon gases from cellulose pyrolysis

The formation of gaseous products has been examined for cellulose over the temperature range of 360–595°C. The evolution of CO, CO₂, H₂, CH₄, C₂H₄, and C₂H₆ was determined as a function of time. The overall kinetic rate constants for decomposition were determined from the formation rates for each gas, as well as the rate constants for the formation of each specific gas. It has been verified that CO and CO₂ are both primary products of decomposition, and further emanate from the same kinetic pathway. By increasing the residence time of the reactor, the production of all gaseous products, including both CO and CO₂, further increased, indicating production by a secondary reaction mechanism. None of the gaseous products, save CO and CO₂, were detected in measurable quantities except at temperatures above which transport limitations had affected the measurement of the kinetic rates.     

Perhalophenyl complexes of palladium(II) containing keto-stabilized phosphorus ylides of the type Ph2P(CH2)nPPh2CHC(O)R

From suitable perhalophenyl derivatives of palladium(II), viz.: Pd(C₆F₅)₂-(SC₄H₈)₂, [Pd(μ-X′) (C₆X₅)₂]₂(NBu₄)₂, [Pd(μ-Cl)(C₆X₅)(SC₄H₈)]₂ (X = F, Cl, X′ = Cl, Br), new complexes of various types have been prepared, viz.: trans-Pd(C₆F₅)₂(Y)₂, Pd(C₆X₅)₂(Y), PdCl(C₆X₅)(Y) (X = F, Cl). The neutral ligand Y is a keto-stabilized phosphorus ylide of the type Ph₂P(CH₂)_nPPh₂CHC(O)R (n = 1, R = CH₃, C₆H₅; n = 2, R = C₆H₅) acting in a terminal monodentate P-donor or a bidentate chelate P,C-donor mode. The reaction of PdCl(C₆F₅)(Y) complexes with HCl leads to the corresponding PdCl₂(C₆F₅)(YH) complexes in which the phosphonium cation [YH]⁺ behaves as monodentate P-donor at its phosphinic end.IR and ³¹P NMR spectroscopy were used to decide the coordination mode of the ligands and, in some cases, to reveal the presence of two isomers.     

Rotational and vibrational distributions of N2(C 3Πu) excited by state-selected Ar(3P2) and Ar(3P0) metastable atoms

The ESR method is used to study the oxidation kinetics of the CH₃, C₂H₅, n-C₄H₉, i-C₄H₉, s-C₄H₉, t-C₄H₉, n-C₆H₁₃, C₆H₁₁, C₆H₅CH₂, CH₃C₆H₄CH₂, and C₆H₅CH₂CH₂ radicals in methanol matrix at 87 K. The reaction kinetics are shown to be describable in terms of a time-dependent rate constant k(t). The contribution from the matrix relaxation to k(t) has been determined. The oxidation rate and the shape of the kinetic curve are independent of the type of the radical. Models interpreting the experimental data are discussed.     

Synthesis and molecular structures of (2-dialkylaminophenyl)alcohols and of 2-phenylaminoalkyl-dimethylaminobenzene derivatives

N,N-Dimethyl-o-toluidine, N,N-dimethylaniline, and N,N-diethylaniline were treated with n-butyllithium-tmeda in diethyl ether-hexane solution to give o-lithioarylamines, which react with various electrophiles (benzophenone, dicyclohexyl ketone, benzaldehyde, and Ph(H)CNPh) to form the corresponding (2-dialkylaminophenyl)alcohols 1-HOCPh₂-2-NMe₂C₆H₄ (1), 1-HOCCy₂-2-NMe₂C₆H₄ (2), 1-HOCPh₂CH₂-2-NMe₂C₆H₄ (4), 1-HOC(H)PhCH₂-2-NMe₂C₆H₄ (6), and 1-HOCPh₂-2-NEt₂C₆H₄ (7), and the 2-phenylaminoalkyl-dimethylaminobenzene derivatives 1-NMe₂-2-NH(Ph)C(H)PhC₆H₄ (3) and 1-NMe₂-2-NH(Ph)C(H)PhCH₂C₆H₄ (5). Compounds 1-7 were characterized spectroscopically (NMR, IR, MS) and by crystal structure determination.     

Collisional depolarization of excited114Cd 5s5p 3 P 1 atoms by collisions with molecular gases

Depolarization of excited¹¹⁴Cd 5s5p ³ P ₁ atoms induced by collisions with various molecular gases (N₂, H₂, D₂, CO, CO₂, CH₄, C₂H₆, C₂H₄) has been investigated using polarized fluorescence spectroscopy. After pulsed optical excitation of the Cd 5³ P ₁ level with appropriately polarized light the temporal behaviour of Zeeman quantum beats has been observed showing the influence of collisional destruction of orientation and alignment. By analyzing the signal curves at different molecular gas pressures the corresponding depolarization cross sections for¹¹⁴Cd atoms in the 5³ P ₁ state have been obtained. With regard to a test of a nuclear spin decoupling model for the collisions the cross sections were compared with previously measured hyperfine structure transfer cross sections of¹¹³Cd 5s5p ³ P ₁ atoms.     

A Comparative 19F NMR study of electronic effects in some fluoroaryl compounds of antimony and bismuth and in their carbon and nitrogen analogues

A number of m- and p-fluorophenyl compounds of type Ar₂QC₆H₄F (Q = Sb, Bi, N and CH; Ar = C₆H₅, C₆H₄F) have been prepared. The ^l0F chemical shifts relative to fluorobenzene have been measured in cyclohexane, chloroform and pyridine for all these compounds. On the basis of the data obtained, the electronic nature of the Ar₂Sb and Ar₂Bi substituents has been studied and compared with that of the corresponding (C₆H₅)₂N and (C₆H₅)₂CH groups. The electronic effect of the Ar₂Sb and Ar₂Bi substituents has been shown to be mainly inductive, its solvent susceptibility being in most cases close to zero relative to both electron- and proton- donating solvents.     

Tin(IV) complexes of schiff bases derived from pentane-2,4-dione or 2-hydroxy-1-naphthaldehyde

The 1∶2 molar reactions of tin(IV) chloride with the Schiff bases, CH₃C(OH):CHC(CH₃):NR and 2 HOC₁₀H₆CH:NR′ (where R=C₂H₅,n-C₃H₇ orn-C₄H₉ and R′=C₆H₅, C₂H₅,n-C₄H₉ ort-C₄H₉) have resulted in the synthesis of SnCl₄·(SBH)₂ type derivatives (whereSBH represents the Schiff base molecule). These have been characterized by elemental analysis, conductivity measurements and IR spectral studies.     

Synthesis and characterization of some ferrocene-containing telluroether ligands: crystal structure of 1,1′-bis(phenyltelluro)ferrocene

A series of five monodentate ferrocene tellurium ligands of the type Fe(C₅H₅)(C₅H₄TeR) and five bidentate 1,1′-disubstituted ferrocene tellurium ligands of the type Fe(C₅H₄TeR)₂ (R = Me, ⁿBu, C₆H₅, p-MeOC₆H₄, p-EtOC₆H₄) has been prepared by the reaction of 1,1′-dilithioferrocene with the appropriate ditellurides R₂Te₂. The ligands have been characterized by their elemental analyses, ¹H and ¹³C NMR spectra, mass spectra and cyclic voltammetry studies. The structure of Fe(C₅H₄TeC₆H₅)₂ has been determined by single-crystal X-ray diffraction study.     

Investigation of the Interaction Between N-benzyl Piperidones and Bovine Serum Albumin by Spectroscopic Approaches

Fluorescence and ultraviolet spectroscopies were applied to investigate the interaction between five N-benzyl piperidones (NBP) and bovine serum albumin (BSA) under imitated physiological conditions. The experimental results show that these NBPs have a static fluorescence quenching effect on the endogenous fluorescence of BSA at the temperatures 302 and 310?K. According to the fluorescence quenching theory, the Stern?CVolmer quenching constant (K _SV), the binding constant (K _a), and the number of binding sites (n) were obtained. Also, the effect of substituents on the binding capacity between NBP and BSA is in the order: C₆H₅?<?4-CH₃OC₆H₄?<?4-CH₃C₆H₄?<?2,4-Cl₂C₆H₃?<?4-ClC₆H₄. The corresponding thermodynamic parameters (??G, ??H, and ??S) were obtained at two different temperatures and indicate that hydrogen bonding and van der Waals forces play main roles in stabilizing the BSA?CNBP complex. The binding distance between the tryptophan residue in BSA and NBP was found to be much <7?nm based on the F?rster theory of non-radiation energy transfer. The effect of NBP on the conformation of BSA was analyzed as well by synchronous fluorescence spectroscopy.     

Group IB organometallic chemistry: XXXIII. ArAuPPh3, ArAu(CNR), (ArAu)n and Ar4Cu2Au2 compounds in which the aryl group contains 2-MeO, 2,6-(MeO)2, 2-Me2N, 2-Me2NCH2 and (S)- or (R)-2-Me2NCHMe substituents as potential ligands

The synthesis and structural characterization by ¹H NMR and ¹⁹⁷Au Mössbauer spectroscopy as well as by chiral labelling of the built-in ligands of three different types of arylgold(I) compounds is described.¹⁹⁷Au Mössbauer data revealed that the benzyl- and arylgold(I) triphenylphosphine complexes which bear potential coordinating substituents at an ortho position still contain linearly coordinated Au^I with 2c-2e gold(I)carbon bonds. The observation of isochronous NME resonances in (S)-2-Me₂NCH(Me)C₆H₄AuPPh₃ confirms that no additional intramolecular AuN coordination occurs in solution. Preliminary results of an X-ray diffraction study of 2,6-(MeO)₂C₆H₃AuPPh₃ are reported (R = 0.040, PAuC₁ angle 172.6°. Unsymmetrical AuC₁C₂ and AuC₁C₆ angles of 126.4 and 117.4°, respectively).Pure, uncomplexed arylgold(I) compounds have been isolated from the reaction of diarylgoldlithium compounds (arylaurates) with trimethyltin bromide. (S)-2-Me₂NCHMeC₆H₄Au has a dimeric structure which most likely consists of two monomeric units associated by intermolecular AuN coordination thus forming a ten-membered chelate ring. The structure of insoluble 2-Me₂NCH₂C₆H₄Au and 2-Me₂NC₆H₄Au are less clear. The former compound probably has a structure similar to (S)-2-Me₂NCHMeC₆H₄Au (IS/QS values for two-coordinate Au^I centers). However, the strongly deviating IS and QS values of 2-Me₂NC₆H₄Au indicate that a polynuclear structure for this compound similar to that proposed for 2-Me₂NC₆H₄Cu cannot be excluded (a polymeric structure containing 2-Me₂NC₆H₄ groups which span three Au atoms by 3c-2e Au₂C bonds and AuN coordination).The mixed Au/Cu cluster (2-Me₂NCH₂C₆H₄)₄Au₂Cu₂ is accessible via the $\text{1}\text{2}$ reaction of (2-Me₂NCH₂C₆H₄)₄Au₂Li₂ with CuI. Molecular weight and ¹H NMR studies point to a tetranuclear structure in solution, while mass spectrometry shows fragment ions with m/e corresponding to (2-Me₂NCH₂C₆H₄)₃Au₂Cu₂⁺, (2-Me₂NCH₂C₆H₄)₃Cu₂Au⁺, (2-Me₂NCH₂C₆H₄)₂CuAu₂⁺ and of (2-Me₂NCH₂C₆H₄)₂Au⁺.     

The electronic properties of isocyanides at rhenium—dinitrogen binding sites. Preparation and redox properties of the isocyanide complexes trans-[ReCl(CNR)(Ph2PCH2CH2PPh2)2]

The isocyanide complexes trans-[ReCl(CNR)(dppe)₂] (R  Me, Bu^t, C₆H₄CH₃-4, C₆H₄CH₃-2, C₆H₄Cl-4, C₆H₄OCH₃-4 and C₆H₃Cl₂-2,6; dppe  Ph₂PCH₂CH₂PPh₂) have been prepared by isocyanide displacement of dinitrogen from the parent complex trans-[ReCl(N₂)(ddpe)₂]. Their redox properties have been studied by cyclic voltammetry and are interpreted on the basis of the electronic properties and the geometry of the ligating isocyanides which are believed to be bent in these complexes, appearing to exhibit ligand parameter (P_L) values ca. +0.3 V higher than those which would be expected for linear geometry. A very high polarisability (B ? 3.4) is observed for the {ReCl(dppe)₂} site.     

Darstellung und Charakterisierung der Fulleren-Kokristallisate C60 · 12 C6H12, C70 · 12 C6H12, C60 · 12 CCl4, C60 · 2 CHBr3, C60 · 2 CHCl3, C60 · 2 H2CCl2

Synthesis and Characterization of the Fullerene Co-Crystals C₆₀ · 12 C₆H₁₂, C₇₀ · 12 C₆H₁₂, C₆₀ · 12 CCl₄, C₆₀ · 2CHBr₃, C₆₀ · 2CHCl₃, C₆₀ · 2H₂CCl₂ By crystallization of fullerenes from non-polar solvents (C₆H₁₂, CCl₄, CHBr₃, CHCl₃, H₂CCl₂) compounds of the following compositions were obtained: C₆₀ · 12C₆H₁₂, C₇₀ · 12C₆H₁₂, C₆₀ · 12CCl₄, C₆₀ · 2CHCl₃, C₆₀ · 2CHBr₃ and C₆₀ · 2H₂CCl₂. Lattice parameters have been determined by X-ray diffraction of powder samples; according to single-crystal examinations on C₆₀ · 12C₆H₁₂, C₆₀ · 12CCl₄ and C₆₀ · 2CHBr₃ the fullerene is orientationally disordered. C₆₀ · 12C₆H₁₂, cubic, a = 28.167(1) Å; C₇₀ · 12C₆H₁₂, cubic, a = 28.608(2) Å; C₆₀ · 12CCl₄, cubic, a = 27.42(1) Å; C₆₀ · 2CHBr₃, hexagonal, a = 10.212(1), c = 10.209(1) Å; C₆₀ · 2CHCl₃, hexagonal, a = 10.08(1), c = 10.11(2) Å; C₆₀ · 2H₂CCl₂, tetragonal, a = 16.400(1) Å, c = 11.645(7) Å.     

Some hydrogen atom abstraction reactions of CF2H and CFH2 radicals,and the C?H bond dissociation energy in CF2H2

By photolyzing (CF₂H)₂CO and (CFH₂)₂CO the hydrogen atom abstraction reactions of CF₂H radicals with (CF₂H)₂CO, H₂, D₂, CH₄, C₂H₆, n? C₄H₁₀ and iso? C₄H₁₀, and the reactions of CFH₂ radicals with (CFH₂)₂CO and n? C₄H₁₀, have been studied. Arrhenius parameters for these reactions are compared with related systems. From a knowledge of the activation energies for the forward and reverse reactions a value of the bond dissociation energy, D(CF₂H? H) = 97.4 ± 1.3 kcal mole^?1 at a mean temperature of 543°K is obtained. This value is subject to much uncertainty due to possible compensation effects in the Arrhenius parameters. These effects are discussed for this and the other reactions, and the data suggest that D(CF₂H? H) is approximately 100 kcal mole^?1, and that D(CFH₂? H) is very similar. Other literature data tend to confirm these approximate values.